The present invention relates to an industrial vehicle including a hydraulic actuator and a hydraulic pump that is driven by an engine and a method for controlling the industrial vehicle.
A forklift is one example of an industrial vehicle that includes an engine, a hydraulic pump driven by the engine, and a hydraulic mechanism that operates a hydraulic actuator by hydraulic oil discharged from the hydraulic pump. The forklift includes, for example, a lifting hydraulic cylinder, which is a hydraulic actuator that lifts and lowers forks, and a tilting hydraulic cylinder, which is a hydraulic actuator that tilts a mast. When the hydraulic pump is driven by the engine, an increase in the load on the hydraulic pump may reduce the engine torque. This may result in insufficient engine torque and stall the engine. Japanese Laid-Open Patent Publication No. 2012-62137 describes an example of a structure that obviates such engine stalling.
However, the structure of the '137 publication opens a discharge pipe of the hydraulic pump after detecting a reduction in the engine speed. Thus, the engine speed is further reduced before the load on the hydraulic pump is reduced by opening the discharge pipe. Thus, the structure of the '137 publication fails to obviate engine stalling.